Aggressive technology scaling for high performance integrated circuits has resulted in higher current densities in interconnection lines, which in turn increases power dissipation on a respective substrate. Generally, a significant amount of such dissipated power converts to heat, which thus causes a substantial rise in heat density. Respective different operation modes of each of the functional blocks in a high performance integrated circuit cause temperature gradients on the substrate where the integrated circuit is formed. The above-mentioned scenarios provide a need for a lightweight, robust, and power-efficient on-chip temperature-sensing device that can be used for accurate thermal mapping and thermal management.
To satisfy such needs, a variety of on-chip temperature-sensing devices have been proposed over the years such as, for example, an on-chip thermal sensor. In general, an on-chip thermal sensor is an integral part of an integrated circuit that provides one or more additional layers of protection. The on-chip thermal sensor can be used to detect whether the integrated circuit is being hacked, for example, by sensing a presence of an abnormal temperature. As such, the integrated circuit's security protection can be improved. The on-chip thermal sensor can also be used to provide feedback to other on-chip circuits/components so as to allow those on-chip circuits/components to adjust respective circuit parameter(s) for not generating excessive heat dissipation. Accordingly, the whole integrated circuit (system) can operate more efficiently and reliably.
Conventional on-chip thermal sensors typically utilize a variety of temperature-varying physical effects (e.g., voltage) to detect/measure temperature. Such conventional thermal sensors are subjected to a variety of issues when integrated into an integrated circuit. In an example, one or more diodes (p-n junction devices) are used to measure temperature by comparing respective voltage drops based on a temperature-varying characteristic of the voltage drop. However, integrating the diodes into an integrated circuit typically encounters a variety of issues, e.g., re-allocation of real estate to accommodate the diode(s), high power consumption of the diode(s), etc. In another example, a metal-oxide-semiconductor (MOS) transistor is used as an on-chip thermal sensor by using the MOS transistor's temperature-varying threshold voltage. Although such MOS-based thermal sensors are relatively smaller in size and have lower power consumption, integrating the MOS-based thermal sensors into an integrated circuit still encounters a variety of issues such as, for example, difficulty in scaling with other on-chip components/circuits of the integrated circuit. Thus, conventional on-chip thermal sensors are not entirely satisfactory.